Polish Jackson 3 support

- Improve Javadoc.

- Suppress warnings for "removal".

- Update copyright headers.

- Migrate several tests from:
  - MappingJackson2MessageConverter to JacksonJsonMessageConverter
  - Jackson2JsonEncoder to JacksonJsonEncoder
  - Jackson2JsonDecoder to JacksonJsonDecoder
  - Jackson2SmileEncoder to JacksonSmileEncoder
  - Jackson2ObjectMapperBuilder to JsonMapper and XmlMapper
  - MappingJackson2JsonView to JacksonJsonView
  - MappingJackson2HttpMessageConverter to JacksonJsonHttpMessageConverter
  - MappingJackson2XmlHttpMessageConverter to JacksonXmlHttpMessageConverter

spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/WebSocketMessageBrokerConfigurationSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/SockJsClient.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/TransportHandlingSockJsService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/client/ClientSockJsSessionTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/client/DefaultTransportRequestTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransportTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/frame/SockJsFrameTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,7 +28,6 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class SockJsFrameTests {
 
-
 	@Test
 	void openFrame() {
 		SockJsFrame frame = SockJsFrame.openFrame();

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/transport/session/StubSockJsServiceConfig.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/transport/session/WebSocketServerSockJsSessionTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.